The invention relates to a process for forming an imbricated stream of first and second printed products, in which in each case a first and a second printed product are located substantially congruently one upon the other (double imbricated formation), and to an apparatus for carrying out the process. The invention also relates to an apparatus for forming and removing an imbricated stream of printed products at optionally a first transfer region or a second transfer region, located downstream of the first transfer region.
Printed products, e.g. newspapers, periodicals, magazines, leaflets and the like, are often conveyed, during production, from one process station to the next in a so-called imbricated arrangement. In an imbricated arrangement, one printed product partially overlaps the printed product which is located beneath, further forward in the conveying direction, with the lateral edges of the printed products, as seen in the conveying direction, terminating essentially flush with one another. In the case of folded printed products, a distinction is made between a forward imbricated arrangement, in which the folded edge of each printed product is located at the front in the conveying direction, and a rearward imbricated arrangement, in which the fold is located at the rear in the conveying direction. The folded edge here may be located at the top or bottom.
Imbricated arrangements are formed, for example, by printed products being individually gripped from a processing drum or from a printed product stack and deposited at regular time intervals on a conveying belt of the removal conveyor, which moves continuously at a predetermined speed. EP-A 0 686 463 and EP-A 0 753 386, and corresponding U.S. Pat. Nos. 5,715,737 and 5,826,476, for example, disclose the operation of individual printing products coming from a processing drum being gripped by grippers arranged at regular intervals on an intermediate conveyor.
For some applications, it is desirable for the printed products not to be conveyed at regular intervals from one another, in which case each printed product just partially overlaps with the one in front and the one behind (single imbricated formation), but to be combined into small groups as a double or multiple imbricated formation. In each case two or more printed products in this case essentially overlap one another, e.g. by being positioned substantially congruently one upon the other. One group, in turn, then only partially overlaps the following group of printed products.
The invention has an object of providing a process and an apparatus for forming an imbricated stream of groups of printed products. The intention, in particular, is to provide a process and an apparatus for forming a double imbricated stream, in which such a group comprises two printed products.
The invention also has the object of further developing a known apparatus for forming an imbricated stream such that it is possible to achieve a higher level of flexibility in respect of the transporting direction and of the type of imbricated formation removed.
The above and other objects and advantages of the invention are achieved by the provision of a process and apparatus for forming an imbricated stream of first and second printed products in a double imbricated formation, wherein, first and second printed products are individually gripped alternately by an intermediate conveyor and deposited on a conveying belt of the removal conveyor. In each case, a second printed product is fed to the removal conveyor such that it comes to rest substantially congruently, i.e. with maximum overlap, on a first printed product which has already been deposited on the removal conveyor and overlaps the preceding printed product in an imbricated manner. The xe2x80x9cfirstxe2x80x9d printed product referred to hereinbelow in each case is the first deposited printed product, which is located at the bottom in a group of printed products. The xe2x80x9csecond,xe2x80x9d printed product referred to is that which rests with maximum overlap on the first printed product. First and second printed products may, although not necessarily, be different. They are different, for example, when different sub-products are grouped to produce a main product and are the same when all that is required is further processing of stacks.
As the intermediate conveyor, use is preferably made of a gripper conveyor with grippers arranged one behind the other in the conveying direction. The xe2x80x9cfirstxe2x80x9d grippers referred to are the grippers which grip a first printed product, and the xe2x80x9csecondxe2x80x9d grippers are those for accommodating a second printed product. The first and second grippers may be of identical construction. According to the invention, first grippers with first printed products gripped thereby alternate with second grippers with second printed products gripped thereby. If the intention is to form an imbricated formation with more than two printed products per group, then xe2x80x9cthirdxe2x80x9d, xe2x80x9cfourthxe2x80x9d, etc. printed products are correspondingly positioned on the first and second printed products.
According to the invention, the first and second printed products, which come from a processing drum or from a printed-product stack for example, are individually gripped one behind the other by the intermediate conveyor, which conveys at a conveying speed V1. In this process step, a stream of printed products which are spaced apart from one another approximately by the same conveying spacing d is formed. The grippers of the intermediate conveyer preferably run along a closed circulatory path. In a second process step, in a transfer region, in each case a first printed product is fed, for example with the associated first gripper opening, to a conveying belt of the removal conveyor, which conveys at a conveying speed V2. In a third process step, in each case a second printed product is fed to the conveying belt such that it comes to rest congruently on a first printed product which has already been deposited.
In order for first and second printed products to be positioned congruently one upon the other, either first and second printed products are released at two transfer locations spaced apart from one another in the conveying direction. For this purpose, the spacing (x2xe2x88x92x1) between the transfer locations is adapted to the conveying speeds V1, V2 of the intermediate and removal conveyors, the conveying spacing d in the transfer region and the conveying directions relative to one another. x1, x2 are the x coordinates of the first and second transfer locations, respectively, the alignment of the removal conveyor defining the x axis. It is preferably more or less the case that
D(V1xe2x88x92V2)=V2d,
where V1, and V2, with the same conveying directions, have the same signs. With pronounced curvature of the circulatory path of the intermediate conveyor in the transfer region, V1 is the speed component in the conveying direction of the removal conveyor.
As an alternative, all the printed products are transferred at a joint transfer location. In this case, in each case a second printed product is pushed congruently onto a first printed product in each case by means of an additional conveyor, which conveys at least substantially at double the conveying speed Vxe2x80x2=2V2 of the second conveyor.
The apparatus according to the invention contains at least one intermediate conveyor with grippers which are moved along a circulatory path and are intended for gripping printed products and supplying the printed products to a transfer region, and a removal conveyor which is designed as a belt conveyor with a conveying belt and is intended for receiving the printed products in the transfer region and removing the printed products, for example, to a further processing station. The apparatus according to the invention also contains at least one initiating means for initiating in each case two successive grippers of the intermediate conveyor in the transfer region, initiation operations taking place at the same transfer location at successive points in time or at spaced apart transfer locations.
An advantage of the invention is that a double or multiple imbricated arrangement can be achieved just by straightforward conversion of known transporting apparatuses. This simplifies the further processing of the products since the printed products do not have to be grouped additionally by means of independent apparatuses.
In a development of the process according to the invention, the printed products are deposited on the conveying belt of the removal conveyor, or on printed products which have already been deposited thereon, from above, the conveying directions either being the same or opposite to one another. In this variant, a forward imbricated arrangement, in which the folds or the gripped edges are located at the front in the conveying direction can be formed by the grippers being pivoted such that the gripped edge is oriented in the conveying direction of the removal conveyor. In order to form a double forward imbricated arrangement, use is preferably made of the process variant of two transfer locations.
In order to produce a rearward imbricated formation, the printed products are preferably transferred at a joint transfer location, the non-gripped, free edge of the printed products then being located at the front in the conveying direction of the removal conveyor.
In order to change over from a forward imbricated formation to a rearward imbricated formation or to change the removal direction, an apparatus for carrying out the process preferably has two removal conveyors. Specific control of the grippers and/or of initiators of the intermediate conveyor makes it possible for printed products to be transferred optionally to the first or to the second removal conveyors. For this purpose, the upstream removal conveyor may be displaced in order to make it easier for printed products to be conveyed onto the further removal conveyor.
The changeover is advantageously made from a double imbricated stream to a single imbricated stream, in which first and second printed products only partially overlap one another, by the grippers assigned to the first and second printed products being opened at a joint transfer location, with the result that first and second printed products come to rest on the conveying belt of the removal conveyor at constant spatial intervals. In the process variant with just one transfer location, in order to change over to a single imbricated stream, the pushing-on operation by means of the additional conveyor is dispensed with. For this purpose, the additional conveyor is deactivated or its conveying speed is reduced to the conveying speed of the removal conveyor. It is thus advantageously possible for a single apparatus, depending on requirements, to produce a single or multiple imbricated stream merely by virtue of the actuation being changed. The apparatus according to the invention thus has a high level of flexibility.